CN111871375A - Preparation method and application of biochar with efficient atrazine adsorption performance - Google Patents

Abstract

A preparation method and application of biochar with efficient atrazine adsorption performance belong to the field of environment functional materials and biomass resource utilization. The method comprises the following steps: mixing MgCl₂·6H₂O is dissolved in (CH)₂OH)₂Adding cetyl trimethyl ammonium bromide into the aqueous solution, stirring, adjusting the pH value to 10-11, continuously stirring, standing, centrifuging, and drying the precipitate to obtain the nano MgO precursor. Mixing the dry camphor tree fallen leaves and the nano MgO precursor in water, stirring and then performing ultrasonic treatment to obtain the modified biomass. The biomass is placed in a tube furnace for calcination. Washing the biochar with 0.01M HCl to remove the unloaded MgO, and drying to obtain the modified deciduous biochar MgO-LBC. Hair brushThe method has the advantages of simple process, stable preparation raw material source, low cost and the like, provides a new way for resource utilization of sludge, provides a new AT adsorbent, and has good environmental effect and social effect.

Description

Preparation method and application of biochar with efficient atrazine adsorption performance

Technical Field

The invention belongs to the field of environment functional materials and biomass resource utilization, and particularly relates to a modified fallen leaf biochar material as well as a preparation method and application thereof.

Background

Atrazine (AT) is used as a high-efficiency herbicide for preventing and killing various gramineous and broadleaf weeds, is widely applied to dry field crops such as corns, broomcorn, woodland and the like, but residual AT on the surfaces of crop leaves and in soil can enter a water body environment along with runoff. The existing research proves that AT is an endocrine disrupter, can induce male sex, can increase the cancer probability even if a human body contacts for a long time, and the AT has the characteristics of long half-life period, high mobility, good chemical stability and the like, so that the AT can exist in the water environment widely and for a long time, and therefore, the promotion of an efficient and environment-friendly method for removing the AT in the water body is imperative.

AT present, various modification methods are developed and applied to improve the AT adsorption performance of the biochar, common acid modification or alkali modification is simple to operate, but the AT adsorption performance of the biochar is not obviously improved, though the AT adsorption performance can be greatly improved by loading graphene-like porous carbon on the biochar, the extensive application of the methods is limited by expensive cost, and meanwhile, the regeneration of materials still has a challenge. Meanwhile, no report about the improvement of the adsorption performance of the biochar on AT by loading metal oxide is found, so that the invention adopts the mode of loading nano MgO on the biochar to improve the adsorption capacity of the biochar on AT, and the MgO is selected because of the advantages of cheap raw materials, safety, environmental protection and the like. To date, MgO modified biochar (MgO-BC) shows excellent performance in removing phosphate or heavy metal in water body, mainly because the introduction of MgO increases the oxygen-containing functional group of biochar, enhances the interaction between the biochar and pollutant or forms a complex on the surface, and the research shows that the oxygen-containing functional group on the biochar also has crucial importance for the biochar to adsorb ATTherefore, it is feasible to improve the adsorption performance of AT by loading nano MgO on charcoal, and the adsorption of AT by MgO-BC is rarely reported AT present. The invention takes the fallen leaves of camphor trees as raw materials and is compounded with nano Mg (OH)₂Modified biochar (MgO-LBC) is prepared by a high-temperature slow pyrolysis method, and is applied to AT adsorption removal, so that a new way is provided for improving the preparation of biochar for AT adsorption removal in water, and the resource utilization of camphor tree fallen leaves is realized.

Disclosure of Invention

In view of the above problems and technical analysis, an object of the present invention is to provide a method for preparing a modified fallen leaf biochar material, which is simple to operate and easy to obtain raw materials, and the prepared MgO-LBC has a large specific surface area and a large total pore volume. The invention also aims to provide the application of MgO-LBC, which not only realizes the resource utilization of camphor tree fallen leaves, but also provides a novel AT adsorbent.

In order to achieve the first object, the invention adopts the following technical scheme:

a preparation method of biochar with efficient atrazine adsorption performance comprises the following steps:

(1) mixing MgCl₂·6H₂O is dissolved in ethylene glycol (CH)₂OH)₂Mixing with deionized water according to the volume ratio of 1: 1; wherein MgCl₂·6H₂The concentration of O in the mixed solution was 0.05 mol/L.

(2) Cetyl trimethyl ammonium bromide was added to the mixed solution of step (1) and stirring was continued for 30 min. Then adding NH₃·H₂Adjusting the pH value of the solution to 10-11 by O, and continuously stirring for 6 h; wherein the concentration of cetyl trimethyl ammonium bromide in the total solution is 0.0125g/mL, which acts as a dispersant to prevent Mg (OH) from forming during the reaction₂Sedimentation occurs.

(3) And (3) standing the mixed solution in the step (2) for 3d, centrifuging at 12000rpm, taking out the precipitate, and drying at 80 ℃ for 12h to obtain the nano MgO precursor.

(4) Mixing powdered dry camphor tree fallen leaves and the nano MgO precursor (10:1, m/m) in the step (3) in deionized water, continuously stirring for 1h, and performing ultrasonic treatment for 30min to obtain modified biomass; wherein the mass concentrations of the powdery dry fallen leaves and the nano MgO precursor in the step (3) in the deionized water are 0.05g/mL and 0.005g/mL respectively.

(5) And (4) placing the modified biomass obtained in the step (4) into a tubular furnace, slowly heating to 500 ℃ at a speed of 10 ℃/min, and continuously calcining for 2h at the temperature.

(6) And (4) washing the biochar obtained in the step (5) by 0.01M HCl, and drying in a drying oven at 80 ℃ to obtain the biochar MgO-LBC with efficient atrazine adsorption performance.

In order to achieve another purpose, the invention adopts the following technical scheme:

an application of a modified deciduous biochar material as an atrazine adsorbent for efficiently adsorbing atrazine.

The invention has the beneficial effects that: the modified deciduous biochar (MgO-LBC) is successfully prepared by a calcining method, is used for adsorbing and removing AT in water, and has the advantages of good chemical stability, large specific surface area and the like. The method has the advantages of simple process, stable sources of the preparation raw materials, low cost and the like, provides a new way for resource utilization of the fallen leaves of the camphor trees, and has good environmental effect and social effect.

Drawings

FIG. 1 is a Field Emission Scanning Electron Micrograph (FESEM) of a modified deciduous biochar material of the present invention.

FIG. 2 is an XRD pattern of the modified deciduous biochar material of the present invention.

FIG. 3 is a graph showing the effect of modified deciduous biochar material of the present invention on AT adsorption AT different pH values.

FIG. 4 is a graph of the kinetics of AT adsorption removal by the modified deciduous biochar material of the present invention.

Detailed Description

The present invention will be described in detail below with reference to examples to enable those skilled in the art to better understand the present invention, but the present invention is not limited to the following examples.

Example 1:

modified fallen leaf biochar material: 10.165g of MgCl were weighed₂·6H₂O dissolved in 200mL (CH)₂OH)₂Adding 2.5g hexadecyl trimethyl ammonium bromide into the mixed solution of deionized water (V/V is 1:1), stirring for 30min on a magnetic stirrer, and then adding NH₃·H₂Adjusting the pH value to 10.5 by O, continuously stirring for 6 hours, standing the obtained mixed solution for 3 days, centrifuging at 12000rpm, taking out a precipitate, and drying at 80 ℃ for 12 hours to obtain the nano MgO precursor. 5g of camphor tree fallen leaf powder ground and sieved by a 100-mesh sieve and 0.5g of nano MgO precursor (10:1, m/m) are mixed in 100mL of deionized water, and the mixture is subjected to magnetic stirring for 1 hour and ultrasonic treatment for 30min to prepare the modified biomass. The biomass was then placed in a tube furnace at a slow rate of 10 ℃/min up to 500 ℃ and calcined at this temperature for 2 h. And then washing the biochar by using 0.01M HCl to remove the unloaded MgO, and drying at 80 ℃ to obtain the modified deciduous biochar MgO-LBC.

SEM analysis results (figure 1) of the MgO-LBC adsorbing material show that the MgO-BC surface is rough, and spherical nano MgO particles uniformly grow on the surface of the biochar. The XRD analysis results of LBC and MgO-LBC are shown in FIG. 2, and compared with LBC, MgO-LBC has diffraction peaks at 42.88 degrees and 62.38 degrees of 2 theta, which are respectively corresponding to the main characteristic peaks of the (200) and (220) crystal planes in the MgO structure, and the MgO particles are successfully loaded on the surface of the camphor tree deciduous biomass.

Example 2:

effect of different pH values on the removal of AT by MgO-LBC adsorption in example 1: 10mg of MgO-LBC was weighed into a brown reaction flask containing 30mL of 20mg/L AT solution, the pH of the solution was adjusted to 2-12 with 0.1M HCl and NaOH AT 1 intervals, and the flask was then placed in a constant temperature shaker AT 298K and shaken for 24 h. After the adsorption was completed, the supernatant was taken. Immediately after the adsorption reaction was completed, the mixture was filtered through a 0.45 μm filter, and the remaining content of AT in the sample was measured by a liquid chromatograph. As shown in FIG. 3, MgO-LBC has better adsorption performance for AT than LBC, and the adsorption amount is 18.3mg/g AT pH 4 AT the maximum, and decreases with increasing pH AT pH 4 or higher.

Example 3:

kinetics study of the MgO-LBC prepared in example 1 for adsorption removal of AT: weighing 20mg of MgO-LBC, adding the MgO-LBC into a brown reaction bottle containing 60mL of AT solution with the concentration of 20mg/L, adjusting the pH value of the solution to be 4, then placing the reaction bottle in a constant temperature oscillator with the temperature of 298K, shaking for 360min, taking supernatant liquid AT different time periods (1min, 5min, 10min, 30min, 60min, 120min, 180min and 360min), filtering by using a 0.45 mu m filter membrane, and determining the residual content of AT in the sample by a liquid chromatograph. As shown in FIG. 4, the adsorption rate was faster before 30min, then the adsorption rate began to decrease, and finally the equilibrium was reached around 100min, AT which the adsorption amount of LBC to AT was only 8.13mg/g, while the adsorption amount of MgO-LBC to AT reached 18.7 mg/g.

Claims (2)

1. The preparation method of the biochar with the efficient atrazine adsorption performance is characterized by comprising the following steps of:

(1) mixing MgCl₂·6H₂O is dissolved in (CH)₂OH)₂Mixing with deionized water according to the volume ratio of 1: 1; wherein MgCl₂·6H₂The concentration of O in the mixed solution is 0.05 mol/L;

(2) adding cetyl trimethyl ammonium bromide into the mixed solution in the step (1), and continuously stirring for 30 min; then adding NH₃·H₂Adjusting the pH value of the solution to 10-11 by O, and continuously stirring for 6 h; wherein the concentration of the hexadecyl trimethyl ammonium bromide in the total solution is 0.0125 g/mL;

(3) standing the mixed solution obtained in the step (2) for 3d, centrifuging at 12000rpm, taking out the precipitate, and drying at 80 ℃ for 12h to obtain a nano MgO precursor;

(4) mixing powdered dry camphor tree fallen leaves and the nano MgO precursor (10:1, m/m) in the step (3) in deionized water, continuously stirring for 1h, and performing ultrasonic treatment for 30min to obtain modified biomass; wherein the mass concentrations of the powdery dry fallen leaves and the nano MgO precursor in the step (3) in the deionized water are 0.05g/mL and 0.005g/mL respectively;

(5) placing the modified biomass obtained in the step (4) in a tubular furnace, slowly heating to 500 ℃ at a speed of 10 ℃/min, and continuously calcining for 2h at the temperature;

(6) and (4) washing the biochar obtained in the step (5) by 0.01M HCl, and drying in a drying oven at 80 ℃ to obtain the biochar MgO-LBC with efficient atrazine adsorption performance.

2. The use of biochar prepared by the preparation method of claim 1, characterized by the use of a modified deciduous biochar material as an atrazine adsorbent for the efficient adsorption of atrazine.

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